The present disclosure relates to the field of optics. More specifically, the present disclosure concerns front-projection cinema screens.
Movie theater industry guidelines dictate that when a movie is being projected the assembled screen seams should be invisible to the naked eye from a viewing distance of 1 to 1.5 times the screen's height (referred to as the “invisibility” requirement). In order to meet the “invisibility” requirement, the seam gap at each splice can be as large as from about 50 microns to about 70 microns in order for the seam to be unnoticeable by the moviegoer when a movie is playing, affording an undistracted content delivery and viewing experience.
In the fabrication of large-format reflective front-projection cinema screens for motion-picture applications, minimizing or eliminating variations inherent in the final manufactured screen material is a challenging process—the optical integrity of the screen is important as well as the absence of visible non-uniformities. Also, owing to the screen's weight, the seams in a screen should be able to withstand a constant stretching load in order to meet the minimum industry standards for front-projection cinema screens.
Currently produced commercial theater-sized (10′×20′, 20′×40′ and 40′×85′ (IMAX) are common sizes) large-format front-projection cinema screens are made utilizing common seaming techniques such as ultrasonic welding, thermal welding or lamination to a back supporting material. Such backing aids are undesirable because they introduce weight and make the matching of acoustic perforations difficult.
Projection screens can be hung vertically to present a viewing surface to an audience in stadium seating. While a worker of ordinary skill in the art may vary the following directions in accordance with his needs, the exemplary embodiment describes structures and processes directed to a vertically hung dimensionally stable viewing surface. For commercial use in theatres, the vertically hung viewing surface described can remain flat without curling, buckling, or wrinkling under the influence of constant vertical and horizontal tensile loads of 4 to 6 pounds per inch over its useful (10+ year) lifetime. In particular, preserving structural integrity in these large formats, one aspect of the present invention, can minimize distortions to the motion picture image that would otherwise occur at the seams of the splices between viewing screen segments.